Aluminum is the most abundant metallic element in Earth’s crust, but it is never found naturally as an element. Instead, it always appears naturally in its oxidized form as a hydroxide we call bauxite.

The extraction of aluminum from bauxite requires three stages. First, the ore is mined. Then it is refined to recover alumina. Finally, the alumina is smelted to produce aluminum. The mining is done via the open-cut method. Bulldozers remove the topsoil, and excavators or other types of power machinery are used to remove the underlying layer of bauxite. The bauxite may be washed to remove clay and other detritus.

Refining is done via the Bayer refining process, named after its inventor, Karl Bayer. Ground bauxite is fed into a digester, where it is mixed with a caustic soda. The aluminum oxide reacts with the soda to form a solution of sodium aluminate and a precipitate of sodium aluminums silicate. The solution is separated from the silicate through washing and pumping, and the alumina is precipitated from the solution, where it appears as crystals of alumina hydrate. The crystals are washed again to remove any remaining solution. Then they are heated to remove water, leaving the gritty alumina.

Smelting is done via the Hall-Heroult smelting process. An electric current is passed through a molten solution of alumina and cryolite, which is in a cell lined at the bottom and top with carbon. This forces the oxygen to combine with the carbon at the top of the cell, making carbon dioxide, while the molten metallic aluminum collects at the bottom of the cell, where it is siphoned off, cleaned up, and cast into bars, sheets, or whatever form is needed.

As with all mining of metals, bauxite mining presents certain hazards. Along with the usual mining issues of degraded soil and polluted runoff, chief among these hazards is the omnipresent bauxite dust, which clogs machinery and lungs, sometimes for miles around the mining site. Jamaica and Brazil have seen widespread protests recently against the major bauxite mining companies, which continue to insist that no link between bauxite dust and pervasive lung problems has been proved.

1. Based on the information in the second paragraph, you can conclude that bauxite is located

A. within the topsoil
B. wherever clay is found
C. below the topsoil
D. below Earth’s crust
E. along riverbanks

The OA is C

2. According to the passage, all of these are produced by the Bayer process except

A. sodium aluminum silicate
B. sodium aluminate
C. aluminum manganese
D. alumina hydrate
E. alumina

The OA is C

3. The ideas in the second, third, and fourth paragraphs are related because they are

A. steps in a process
B. examples of a mineral
C. reasons for mining
D. comparisons among theories
E. suggested solutions

The OA is A

4. The process by which aluminum is extracted from bauxite is most similar to which of the following?

A. The building of steel bridges
B. The making of copper tubing
C. The manufacturing of glass
D. The mixing of cement
E. The growth of most grains

The OA is B

5. The author includes the discussion of protests primarily to show that

A. bauxite mining takes place in the Third World
B. workers are starting to fight back against the dangers of mining
C. mining companies have misled people for decades
D. the government of Brazil works with the mining companies
E. miners have a tradition of unionization

The OA is B

6. The tone of the passage suggests that the author would most likely believe which of the following?

A. Bauxite mining poses health problems
B. The United States should use less aluminum
C. Australian bauxite is the best quality
D. Karl Bayer was something of a genius

The OA is A
E. Mining is becoming cheaper and safer